stiffness measurements cnc mk3

[EddyCurrent]

I just tried mine now it's mostly together mechanically. Build thread here http://www.mycncuk.com/forums/gantry...y-eddy-23.html

Using a Mitutoyo digital DTI with 0.01 mm resolution, deflections with 5kg force applied as above.

X 0 mm
Y 0.04 mm
Z 0 mm

I think the Y deflection is due to the ball screw system because wherever I apply 5kg load to the Z carriage I get the same deflection.

[routercnc]

Hi Eddy,

Yes, been following your build - coming along nicely. So with those figures X and Z are >5000N/mm, and Y = 1250N/mm.

The lower Y stiffness could be the mounting angle brackets for the AC bearing but not sure why it is similar as you move around the Z carraige as the moment would be changing. I also notice your ballscrew is right at the back of the gantry which is another reason for it being a bit lower than the other axes as it is the furthest away from the tool with the highest moment compared to the other ballscrews. But if the limited cutting I have done on my machine (with a lower stiffness) is anything to go by it's not a concern.